/****************************************************************************** * * Name: hwtimer.c - ACPI Power Management Timer Interface * *****************************************************************************/ /* * Copyright (C) 2000 - 2012, Intel Corp. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer, * without modification. * 2. Redistributions in binary form must reproduce at minimum a disclaimer * substantially similar to the "NO WARRANTY" disclaimer below * ("Disclaimer") and any redistribution must be conditioned upon * including a substantially similar Disclaimer requirement for further * binary redistribution. * 3. Neither the names of the above-listed copyright holders nor the names * of any contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * Alternatively, this software may be distributed under the terms of the * GNU General Public License ("GPL") version 2 as published by the Free * Software Foundation. * * NO WARRANTY * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. */ #include <linux/export.h> #include <acpi/acpi.h> #include "accommon.h" #define _COMPONENT ACPI_HARDWARE ACPI_MODULE_NAME("hwtimer") /****************************************************************************** * * FUNCTION: acpi_get_timer_resolution * * PARAMETERS: Resolution - Where the resolution is returned * * RETURN: Status and timer resolution * * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits). * ******************************************************************************/ acpi_status acpi_get_timer_resolution(u32 * resolution) { ACPI_FUNCTION_TRACE(acpi_get_timer_resolution); if (!resolution) { return_ACPI_STATUS(AE_BAD_PARAMETER); } if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { *resolution = 24; } else { *resolution = 32; } return_ACPI_STATUS(AE_OK); } ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution) /****************************************************************************** * * FUNCTION: acpi_get_timer * * PARAMETERS: Ticks - Where the timer value is returned * * RETURN: Status and current timer value (ticks) * * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). * ******************************************************************************/ acpi_status acpi_get_timer(u32 * ticks) { acpi_status status; ACPI_FUNCTION_TRACE(acpi_get_timer); if (!ticks) { return_ACPI_STATUS(AE_BAD_PARAMETER); } status = acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block); return_ACPI_STATUS(status); } ACPI_EXPORT_SYMBOL(acpi_get_timer) /****************************************************************************** * * FUNCTION: acpi_get_timer_duration * * PARAMETERS: start_ticks - Starting timestamp * end_ticks - End timestamp * time_elapsed - Where the elapsed time is returned * * RETURN: Status and time_elapsed * * DESCRIPTION: Computes the time elapsed (in microseconds) between two * PM Timer time stamps, taking into account the possibility of * rollovers, the timer resolution, and timer frequency. * * The PM Timer's clock ticks at roughly 3.6 times per * _microsecond_, and its clock continues through Cx state * transitions (unlike many CPU timestamp counters) -- making it * a versatile and accurate timer. * * Note that this function accommodates only a single timer * rollover. Thus for 24-bit timers, this function should only * be used for calculating durations less than ~4.6 seconds * (~20 minutes for 32-bit timers) -- calculations below: * * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes * ******************************************************************************/ acpi_status acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed) { acpi_status status; u32 delta_ticks; u64 quotient; ACPI_FUNCTION_TRACE(acpi_get_timer_duration); if (!time_elapsed) { return_ACPI_STATUS(AE_BAD_PARAMETER); } /* * Compute Tick Delta: * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. */ if (start_ticks < end_ticks) { delta_ticks = end_ticks - start_ticks; } else if (start_ticks > end_ticks) { if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { /* 24-bit Timer */ delta_ticks = (((0x00FFFFFF - start_ticks) + end_ticks) & 0x00FFFFFF); } else { /* 32-bit Timer */ delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; } } else { /* start_ticks == end_ticks */ *time_elapsed = 0; return_ACPI_STATUS(AE_OK); } /* * Compute Duration (Requires a 64-bit multiply and divide): * * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; */ status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000, PM_TIMER_FREQUENCY, "ient, NULL); *time_elapsed = (u32) quotient; return_ACPI_STATUS(status); } ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)